Who lives in here?

A chilly but enjoyable walk at Quarrymill. The girls were speculating about who or what lives in this little hole at the base of a tree. They finally decided it was a lift to take owls to the top. At the duck pond a man with an enormous lens on his camera was eagerly snapping away - turned out it was a kingfisher, which was perched on a branch. He said that even with his lens, he was struggling to shoot it clearly, so I didn't even attempt a photo. But I can assure you it was stunning.